> As well as helping with emissions, the Passat's battery pack provides extra performance
There is another reason to develop that kind of car: Gasoline will get more scarce and expensive as global oil production peaks, especially for countries like Europe or Japan that have none.
"Total world, oil production" www.manicore.com/documentation/petrole/pic_graph42.jpg
"Oil production, EU 27 with/without Norway" www.manicore.com/documentation/petrole/pic_futur_graph3.jpg

Plug-in is hybrids "killer app"

@ Freyr Gunnar
In support of the links in Freyr's post, I would add Gail Tverberg's Our Finite World website,which concentrates on world oil supply, or rather the lack of it, and is a valuable source of pertinent information. Also worth a visit is Chris Martenson's Peak Prosperity website, which provides a valuable take on world economics. His Crash Course and its discussion of oil supply, is particularly pertinent. (Both sites are free regarding the relevant information, but Martenson's has a pay wall for deeper analysis.)
Incidentally, Both of the above sites also raise the issue of copper supply, which is dwindling in terms of ore quality. How that is going to affect the production of electric cars and such like, including hybrids, causes me some concern. I assume that the automotive industry has taken account of this, especially the projected price rise as the supply of good quality ore dwindles even further and we pass a peak of copper supply. Mind you, if Tverberg and Martenson are anywhere near correct in their projections, a lack of copper will be the least of our worries.

I don't understand the hyper inflated numbers. 141mpg? 620 miles on 13.2 gallons of fuel is 46mpg, which is pretty close to what a diesel Passat already gets...so, whats the big deal? Am I missing something here?

@enntense I think that number might be MPGe (MPG equivalent) for the first miles that are done on electric before it goes into hybrid mode.
Basically its something that should be measured in miles/kWh or watts/mile but the auto industry decided the public is too entrenched in "MPG" to understand electricity so that is supposed to be a useful dumbed down metric for them to use to rate electric car efficiency.
Another useful example is the plug-in Prius, in the specs of the car they list it at 95 MPGe and 50 MPG average for hybrid mode.
With plug-in hybrid real world mileage (as in actual gasoline used) actually does get pretty confusing because actual driving is usually too short range to measure in tanks of gas.
Using the Chevy Volt as an example it gets 37 miles on battery before using hybrid mode (which is probably similar to a Prius in mileage). Because people tend to drive a short distance (work, shopping, etc.) and then plug in the car back in, the car can stay in electric mode much longer than the mere 37 miles of range would imply and Volt owners get real world range of about 900 miles per 9 gallon tank of gas, or 100 MPG. But that's different than MPGe.
I wish the convention the industry would use is just listing miles/kWh for electric separate from hybrid MPG. Example:
3 miles/kWh (at 16.5 kWh battery capacity) in electric mode 51/48 city/highway in hybrid mode
Even watts/mile is fine but the MPGe format seems pretty stupid once we apply it to actual EV's but I suppose the figure is supposes to be how many miles you can drive on electric for the cost of a gallon of regular gas.

enntense, It's a plugin hybrid which means at times it runs on pure electric without gas. During those times it gets all its miles without burning any fuel and that is averaged into the mpg equivalency.

I must be missing something.
A fuel consumption of 141 mpg and a fuel tank which holds 13.2 gallons should theoretically allow the car to travel 1,861.2 miles on 1 tank shouldn't it? Not the 620 miles quoted?
620 miles using 13.2 gallons would equate to a 47mpg.

Like many other consumers, I live in an apartment building with no access to charging a car! Give me mpg numbers starting with a full gas tank and an empty battery! Those are meaningful numbers otherwise if you keep charging your battery and never using gas you get infinite mpg, right??? Marketing people... no no no give the real mpg numbers, no mixing apples and pears and posting price only for apples...

more plug-in-car-nonsense.
bob lutz from gm said it himself. electric is good for trucks and busses before it will ever succeed at scale with cars.
hybrid cars , were a nice little stepping stone but ultimately don't offer the consumer much at all, other than the pleasure of a quiet ride. plug-ins are an expensive pointless compromise.
electric power works at scale for bicycles, mini commercial forklifts, and for busses.
the next stage is to utilize them when they are good enough for trucks.
the most successful electric car in the u.s. by numbers is the nissan leaf. how many people do you know that own it?
don't believe me? http://insideevs.com/monthly-plug-in-sales-scorecard/

VW Passat: Ok, if I take the 620 and subtract 30 miles for Electric mode it leaves 590. 590/13,2 gallons = 44.7 mpg on the gas engine. Combined they go 620/13.2 = 46.9 mpg less the equivalent energy to charge the battery. To get 141 mpg you only drive 43.6 miles or 47 km. Maybe they consider that their average daily drive. GM says the average drive is 40 miles per day. I own a VOLT and for 18 months it has averaged 136 mpg fuel only. Last month was 162 mpg with a little less long driving. I expect the VW will average close to the 141 stated but that is very misleading to advertise it.